SPID#: 56 This project has investigated several aspects of maternal behavior and infant development in rhesus, pigtail, and stumptail macaques including the development of maternal responsiveness during pregnancy, social influences on normal and abnormal maternal behavior, mother-infant communication and maternal encouragement of infant independence, and social and hormonal influences on infant development. The dataset for thisproject includes over 1000 hours of focal observation of mothers and infants living in large captive social groups. This project has produced the first quantitative evidence that female interest in infants increases during pregnancy and that macaque mothers encourage their infants to walk independently and to follow. The findings of this research project have improved our understanding of some general principles underlying the mother-infant relationship in primates and the influence exerted by social and physiological variables on parenting and infant development.